KR20020005640A - Concentrically leaded power semiconductor device package - Google Patents

Abstract

The present invention is directed to a concentrically leaded power semiconductor package and includes two or more entirely concentric conductors. The inner conductor may provide an electrical connection at an end opposite the point of attachment with one or more semiconductor elements at one end of the inner conductor. The outer conductor can be pressed on the inner conductor and can be separated by an electrical insulator. Semiconductor devices, such as light emitting diodes (LEDs), are attached to the inner conductor by epoxy gluing or soldering, and may be attached to the outer conductor by bonding wires. The package can be solid cylindrical or square. The package may include additional semiconductor mounting surfaces and two or more conductors.

Description

Semiconductor Packages & Coaxial Packages {CONCENTRICALLY LEADED POWER SEMICONDUCTOR DEVICE PACKAGE}

Current packages for semiconductor devices, such as light emitting diodes (LEDs), are "through the hole" type or surface mount type. These packages are used with printed circuit boards (PCBs), which require special assembly processes to safely mount the semiconductor devices onto the PCB. A soldering process is then applied to electrically and thermally connect the semiconductor leads with the PCB. In the case of LEDs, this PCB connection method powers up the LEDs in the package and turns them on.

Current LED packages have either thin leads (leadframe platforms) or lead-free (PCB platforms that use plated gold or tin traces as a conductive path) for connection with PCBs or hard wires. These current LED packages inevitably have very poor heat transfer and conduction properties in removing the heat generated by the LED chips in the LED package. Thus, current LED packages rarely operate at power levels higher than 0.3 watts.

Current LED packages also have other drawbacks, including a large package footprint. If the flux per package per footprint area is, for example, the dimming factor in the instrument cluster, it is difficult to apply the current LED package. In addition, conventional LED packages are so large that they cannot form a group of LEDs of different colors in the reflection (mixing) chamber closely, so that no special spectral effect and luminous efficiency can be obtained.

Summary of the Invention

Concentrically leaded power semiconductor device packages can eliminate problems in current semiconductor package designs. This package gives the possibility to avoid or minimize the use of soldering processes in application assembly. The package also offers excellent heat dissipation. The package includes a pair of coaxial cylindrical or square wire leads electrically separated by a thin dielectric film. The package does not need to be mounted and powered on the PCB. Leads from this package can be safely mounted on low cost connectors that are designed to function as a heat sink by simply plugging the package into the connector. The connector powers the LEDs, but they also remove the heat generated by the LEDs. This package provides excellent heat transfer and conduction properties to the LEDs packaged inside. This can be done by attaching the LED chip on one end to a cross section of a straight wire (inner wire) at the end of the application and inserting the opposite end of the same wire into the heat sink. Alternatively, an external wire, i.e. a conductor, may be inserted into the heat sink. The diameter and material of the wire can be selected based on the thermal performance of the LED chip package. Thermal composite or grease may be used to reduce the thermal resistance at the interface between the cylindrical surface of the inner wire and the heat sink of the connector. This design architecture allows high-power LEDs to be packaged and operate at high wattage without overheating.

In addition to the coaxial cylindrical or square design, the package may include layers of multiple coaxial conductors. For example, the package may include three concentric cylindrical conductors. This design allows for the use of multiple LEDs. Other variations of the package configuration may include LEDs, semiconductor devices, and resistor devices attached on the cut surface of one of the semiconductors. Such a modification of the package design may be useful for semiconductor lasers, for example.

The technical field relates to package design for mounting semiconductor devices.

DETAILED DESCRIPTION A detailed description will be given with reference to the following drawings in which like elements are denoted by like reference numerals.

1A is a cross-sectional view of a power semiconductor device package concentrically read;

1B is a plan view of a concentrically leaded power semiconductor package showing another mounting configuration for a semiconductor device;

2A through 2C illustrate various optical designs and bonding forms for the package shown in FIG.

3 is another design of a concentric leaded power semiconductor device package.

1A is a cross-sectional view of a concentrically led power semiconductor device package design 10. The concentric leaded power semiconductor device package 20 includes an inner conductor 22 that is circular, square, triangular or any other suitable shape in cross section. The inner conductor 22 comprises an electrical connection end 23 and a mounting surface cross section 25 of the inner conductor 22 at the opposite end from the electrical connection end 23. The outer conductor 24 surrounds the inner conductor 22 and takes the same cross-sectional shape as the inner conductor 22 as a whole. The inner conductor 22 and the outer conductor 24 are separated by the insulating film 26. The insulating film 26 provides electrical insulation between the inner conductor 22 and the outer conductor 24. Insulating film 26 may be, for example, a very thin high temperature dielectric coating.

The inner conductor 22 and the outer conductor 24 can be firmly bonded together with a press fit. The mounting surface 25 of the inner conductor 22 and the mating surface 27 of the outer conductor 24 are machined or cast (stamped) into an overall feature designed for die attachment, wire bonding and optical performance. )do.

Along the length of the package, the outer conductor 24 terminates before the inner conductor 22, thus exposing the inner conductor 22 and the insulating film 26. The insulating film 26 can be removed from the inner conductor 22 and the inner conductor 22 can be plated for electrical and thermal contacts. The entire package 20 may be plated with a nickel bottom and an upper layer 32 of silver, gold or other precious metals for die attach, wire bonding, optical reflection, electrical and thermal contacts, and corrosion resistance. Selective plating and coating of reflective materials can be used to meet the purpose of performance.

1A shows an LED chip 28 attached to the inner conductor 22 at the mounting surface 25. Bonding wire 30 is used to attach LED chip 28 to another conductor 24. The LED chip 28 is attached to the inner conductor 22 using, for example, standard conductive epoxy or soldering. Likewise, the bonding wires 30 may be attached to the LED chip 28 and the outer conductor 24 by epoxy or soldering or standard bonding techniques. The LED chip 28 and bonding wire 30 may be sealed using an epoxy dome 34.

In FIG. 1A, an LED chip 28 is shown with bonding wires 30 as one electrical connection. The LED chip 28 is bonded directly to the inner conductor 22 to form a second electrical connection. Other electrical connection configurations with the package 20 are also possible. For example, all electrical connectors from semiconductor devices such as computer chips can be made on the top surface of the semiconductor device. The LED may also be electrically connected to the package 20 in this manner. Alternatively, semiconductor devices such as LEDs, which typically have electrical connections on their tops, can be flipped (eg by soldering) and bonded directly to the substrate. This configuration (known as a “flip chip”) is shown in FIG. 1B, where the semiconductor element 29 is bonded to the inner conductor 22 ′ and the outer conductor 24 ′. Is shown. It is shown that the inner conductor 22 'and the outer conductor 24' are separated by an insulator 26 'providing insulator isolation. The semiconductor element 29 is electrically connected to the inner conductor 22 'and the outer conductor 24' at the attachment point 30 '. The semiconductor element 39 is bonded by, for example, soldering or epoxy gluing.

Design 10 shows a package 20 inserted into a heat sink 36. The heat sink 36 also acts as an electrical connector for the inner conductor 22. Return power (not shown in FIG. 1A) is attached to the external connector 24. The package 20 is easily inserted into the heat sink 36 by, for example, pressing. In order to improve thermal performance, a thermally conductive material 38, such as thermal grease, is provided at the electrical connection end 23 of the inner conductor 22, so that at the interface between the surface of the inner conductor 22 and the heat sink 36. Reduces the thermal resistance.

In FIG. 1A a heat sink 36 is shown attached to the inner conductor 22. Alternative means for removing the heat generated by the semiconductor devices mounted within the package 20 may also be provided. For example, a heat sink may be connected to the outer conductor 24 instead of or with the heat source 36 connected to the inner conductor 22.

The inner conductor 22 is sized to accommodate special applications. For example, the diameter of the inner conductor can range from about 0.1 mm to about 5 mm in diameter. The inner conductor 22 and the outer conductor 24 may be formed of any suitable conductive material, for example copper.

Since the package 20 is very thin, several packages 20 with different color LEDs can be arranged to achieve color mixing. For example, blue LEDs and green LEDs can be packaged to provide the desired effect of light in different colors. In addition, the LEDs can be packaged to produce white light. Because of the excellent heat dissipation characteristics, the package 20 can be used to provide dimming of the entire white light from the LED.

In the example shown in FIG. 1, the LED chip 28 is packaged in a package 20. However, the package 20 may be used with other electrical components, including semiconductor lasers and other power semiconductor devices, and other separate electrical components including resistors, inductors, and capacitors.

Additional semiconductor devices may be included in the package 20. In one configuration, additional LEDs (not shown in FIG. 1A) may be attached to the inner conductor 20. In other configurations, a third conductor (not shown in FIG. 1A) may be disposed concentric with the outer conductor 24. Thereafter, the semiconductor element may be attached to the second conductor 24 and bonded to the inner conductor 22. In such a configuration, a semiconductor element (for example, LED chip 28) attached to the inner conductor 24 can be bonded to the third conductor.

In another configuration (not shown in FIG. 1A), the fourth and subsequent conductors may be arranged concentrically with the inner, ie first conductor.

2A-2C illustrate the attachment of the bonding wire 30 and the different selection of the cross section 25 of the inner conductor 22. As shown in Figs. 2A to 2C, the LED chip 28 is disposed at the center of the cross section of the inner conductor. Only a small change in the surface area around the LED chip 28 has a large influence on the light emission distribution. As illustrated in FIGS. 2A-2C, three different design choices can be made for the cross section of the inner conductor. FIG. 2A illustrates a flat surface 41, FIG. 2B illustrates a reflective cup 43 which is a shallow concave volume for directing the luminous flux upwards, and FIG. 2C shows the light flux distributed downwards. Illustrates a pedestal 45 type that is a raised surface with respect to the LED chip 28 to have a larger dimming space than the hemisphere.

2A-2C also illustrate a choice for attaching bonding wire 30 to an external electrode. It is shown that the LED chip 28 is die-attached to the center of the inner conductor. However, the stitch bond position with respect to the bond wire 30 can be anywhere in the cross section of the outer conductor, giving the designer great flexibility.

3 shows another power semiconductor device package 50 that is concentrically read. The package 50 includes an inner conductor 52 having a flat surface 53 machined longitudinally along its length. The intermediate conductor 56 partially surrounds the inner conductor 52 and is separated from the inner conductor 52 by an insulating layer 54. The intermediate conductor 56 has a machining surface 57 corresponding to the shape of the surface 53 of the inner conductor 52. The outer conductor 60 partially surrounds the intermediate conductor 56 and is separated from the intermediate conductor 56 by an insulating layer 58. The face 59 of the outer conductor 60 is machined corresponding to the face 57, 53 of each of the intermediate conductor 56 and the inner conductor 52. As a result of this processing, the flat surface 53 is exposed and used for mounting semiconductor elements or other electrical elements. Thus, as shown in FIG. 3, the intermediate conductor 56 and the outer conductor 60 are only partially concentric with the inner conductor 52.

At the surface mount surface 61 of the package 50, it is shown that a semiconductor element 62, which may be an LED chip, is mounted on the intermediate conductor 56. The bonding wire 64 attaches the semiconductor element 62 and the inner conductor 52. The semiconductor device 66 is shown attached to the inner conductor 52, and the bonding wire 68 is shown to attach the semiconductor element 66 and the outer conductor 60. A plurality of semiconductor elements 70 are attached along the flat surface 53 of the inner conductor 52. The bonding wire 72 bonds the semiconductor element 70 to the outer conductor 60. For example, an electrical component 74, which may be a resistor or a capacitor, is also shown attached to the flat surface 53.

There is another option that can be used to attach the semiconductor device to the package 50. For example, a "flip chip" (not shown in FIG. 3) may be soldered or epoxyd between the inner conductor 52 and the intermediate conductor 56. The semiconductor element may be bonded onto the surface 59 of the outer conductor 60 and then connected to the inner conductor 52 by a bonding wire.

The package 50 is particularly useful in applications such as semiconductor lasers because the semiconductor device 70 is arranged in an optimal manner in laser applications. The package 50 may also be used for other applications besides the LED package. For example, electrical components 74 together with semiconductor elements 70, 62, 66 may be used to perform most of the functions currently performed by printed circuit boards.

Power for the semiconductor device shown in the package 50 may be supplied by the inner conductor 52 using a return electrical path (not shown) through the intermediate conductor 56 and the outer conductor 60. The inner conductor 52 can also be used to remove heat generated by the semiconductor elements in the package 50 by inserting the end 75 of the inner conductor 52 into a suitable heat sink (not shown). In addition, one or both of the intermediate conductor 56 or the outer conductor 60 may be connected to the heat sink and used to remove heat. In this other configuration, the length of the intermediate conductor 56 and the outer conductor 60 is longer than the length of the inner conductor 52 to facilitate insertion into the heat sink. In this other configuration, the heat sink may also supply electricity to one or both of the intermediate conductor 56 and the outer conductor 60.

The package 50 shown in FIG. 3 is generally cylindrical and includes three partially concentric conductors. However, the package 50 can be further changed by providing additional mounting surfaces similar to the flat surface 53 around the periphery of the package 50. Alternatively, additional conductors may be added to the package 50, with each additional conductor being entirely concentric with previous conductors. In addition, the electrical configuration of the conductor of the package 50 may be the same or different from that shown in FIG. In another configuration, the package 50 may be a solid rectangle or some other solid, which may be used to mount semiconductor devices and other electrical devices on the surface of the conductor. Any coaxial, concentric or symmetrical configuration of the conductor as a whole can be used to provide a solid semiconductor mounting surface with good heat dissipation properties.

The terminology and description used herein is for the purpose of illustration and not of limitation. Those skilled in the art will recognize that many modifications and equivalents may be made within the spirit and scope of the invention as defined in the claims that follow, and all terms herein are to be understood in their broadest sense unless otherwise indicated. Should be.

Claims (20)

A first conductor having a face and a first length, A second conductor concentrically disposed outward of the first conductor and having a second length; A first insulator disposed between the first conductor and the second conductor, A semiconductor element attached to the cross section of the first conductor and the second conductor Semiconductor package comprising a. The method of claim 1, The semiconductor device is a light emitting diode (LED), and the LED is attached to the second conductor using a bonding wire. The method of claim 1, And wherein the cross section is one of flat, concave and pedestal type. The method of claim 1, The semiconductor device is a flip chip (filp chip). The method of claim 1, And the first and second conductors are one of circular and square cross-sections. The method of claim 1, A third conductor concentrically disposed outward of the second conductor and having a third length; A second insulator separating the third and second conductors, A second semiconductor element attached to the first conductor and the third conductor A semiconductor package further comprising. The method of claim 6, The first and second insulators are polymeric materials, The exposed surface of the first, second and third conductors is coated with one or more coatings using a material comprising nickel, silver and gold. The method of claim 1, The first conductor comprises a flat surface exposed along the first length and an insulated surface along the first length, And the second and third conductors are concentric outwardly of the insulated surface. The method of claim 8, And a plurality of electrical elements mounted on the exposed flat surface, each of the plurality of electrical elements bonded to one of a second conductor and a third conductor. The method of claim 9, And the plurality of electrical elements comprises one or more LEDs. The method of claim 9, And the plurality of electrical elements comprises one or more of a semiconductor laser, a resistor, an inductor, and a capacitor. The method of claim 8, The first conductor is generally cylindrical The insulated surface comprises a curved surface of a cylindrical body, The second and third conductors are concentric outward of the curved surface. Semiconductor package. The method of claim 8, The first conductor is a rectangular solid, The insulated surface comprises any three sides of the first conductor along the first length, The second and third conductors are concentric outward of the insulated surface Semiconductor package. The method of claim 1, Further comprising a heat sink having a socket, One of the first conductor and the second conductor is pressed into the socket, The heat sink supplies power to the pushed conductor Semiconductor package. An inner conductor having a first length and having a first surface for mounting one or more semiconductors, One or more outer conductors at least partially concentric along a portion of the inner conductor length, An insulating material disposed between the inner conductor and each of the one or more outer conductors; One or more semiconductor devices disposed on the first surface Semiconductor package comprising a. The method of claim 15, The inner conductor is, A second surface for mounting semiconductor elements, the second surface being formed along the first length, Further comprising one or more electrical components disposed on the second surface, the electrical components comprising one or more of electrical components separate from the semiconductor components. The method of claim 15, A heat sink connected to the inner conductor, The semiconductor package further comprising an optical coating disposed on one or more of the one or more semiconductor devices. An inner conductor comprising a first surface for mounting the electrical components and an electrical connection for connecting the package to a power source; One or more outer conductors coaxially outward with the inner conductor as a whole An electrical insulator disposed between the inner conductor and the one or more respective outer conductors Coaxial package for mounting electrical components comprising a. The method of claim 18, The inner conductor is solid solid with cross sections and one or more sides, The first surface is on one cross-section, The inner conductor comprises a second surface for mounting the electrical component, The second surface is formed on one or more of the one or more sides, The one or more electrical elements are disposed on the second surface Coaxial package for mounting electrical components. The method of claim 18, A heat sink connected to at least one of the inner conductor and the at least one outer conductor; One or more electrical elements disposed on the first surface and bonded to the one or more external conductors; A conductive coating disposed on an exposed surface of the inner conductor and the one or more outer conductors Coaxial package for mounting the electrical component further comprising.